1. Field of the Invention
The present invention relates to an endoscope including a fluid jetting nozzle that jets a fluid toward an observation window.
2. Description of the Related Art
An endoscope includes, at a distal end portion of an insertion part to be inserted into a subject, an observation window for allowing image light of the subject to be loaded therethrough, an illumination window for irradiating the subject with illumination light, and a fluid jetting (air supply and water supply) nozzle that jets a fluid (washing water or air) toward the observation window. The observation window and the fluid jetting nozzle are arranged on a flat surface orthogonal to an axial direction of the insertion part. Additionally, the pair of illumination windows is arranged at positions substantially symmetrical with respect to the observation window.
In the related art, it is general that the surface of the observation window that becomes a light incidence plane is arranged substantially in the same plane as the flat surface of the insertion part. Since a liquid or dirt within a subject adheres to the surface of the observation window, water is jetted from a jetting port of the fluid jetting nozzle to flush the dirt from the observation window, and air is jetted from the jetting port to blow away waterdrops remaining on the surface of the observation window. Since observation is not easily performed if dirt or waterdrops remain on a portion of the observation window, a fluid jetted from the fluid jetting nozzle preferably spreads over the entire surface of the observation window.
For this reason, in an endoscope described in JP2003-210388A, the surface of an observation window is disposed so as to protrude by a predetermined height with respect to the flat surface of an insertion part, and an inclined portion that inclines such that the height thereof becomes larger gradually toward the surface of an observation window from the flat surface is formed over the entire circumference of a peripheral edge of the observation window. Since a fluid jetted from a jetting port of a fluid jetting nozzle collides with an inclined surface of the inclined portion and flows smoothly toward the surface of the observation window, the fluid can be spread on the entire surface of the observation window. The fluid passed through the surface of the observation window flows down an inclined surface opposite to the fluid jetting nozzle, and flows to the flat surface. By providing the inclined portion in this way, the cleanability of the observation window, and removal of water to be jetted is improved. Additionally, in an endoscope described in JP2007-330529A, a distal end face of a protruding stepped portion (stepped portion) that protrudes by a predetermined height from a flat surface is provided with an observation window, a wall portion of the protruding stepped portion is formed with an inclined surface, and a fluid jetting nozzle is arranged so as to face this inclined surface. This enables a fluid to be applied to an inclined surface so as to guide the fluid to the observation window.